This invention relates to a method and apparatus for controlled programmable electronic winding of yarn in the textile industry. More particularly, this invention relates to a method and apparatus for yarn winding in which the geometry of a yarn package is variably controlled electronically according to a predetermined program. Still more particularly, this invention relates to an automatic yarn winding system which is electronically programmable to achieve pre-programmed density profiles in a yarn package which are uniform in shape, density, and weight averages between take-up packages made of the same yarn.
In the textile industry, yarn is generally packaged for various steps in textile processing as a plurality of wraps of yarn disposed about a core. The ideal characteristics of a package of yarn usually depend upon the end use of the package and the characteristics of the yarn so that yarn packaged for weaving or warping may be packaged differently than yarn intended for dyeing. By way of example, a package of yarn for weaving should usually have a mild wrap angle about the core and the yarn-to-yarn friction should be minimized during unwinding. Such a weaving package should also usually be as heavy as possible and include a workable transfer tail in order to minimize labor. In contrast, a package of yarn destined to be dyed should be porous in order to allow the dye liquor to flow through the packaged yarn with a minimum of resistance and a resulting minimum loss of pressure. Thus, a number of machines and devices have been developed for winding yarn in such packages.
Generally, such winding machines have been of two types, i.e., conventional winding machines which generally include either a grooved drum or a cam guide for the yarn, and so-called precision winding machines which include a propeller driven with a constant wind ratio. A particularly suitable winder assembly wherein the winder is controlled primarily mechanically is available from Sharer Textile Machine Works, Ltd., Switzerland. In that winder, yarn from a supply package is provided through a mechanical tensioner which has a fixed tension to the propeller to be wound at a fixed, constant wind ratio on a package. To vary the wind ratio, the gears connecting the drive to the propeller must be changed. In addition, the back pressure on the yarn exhibited by the back pressure system of the machine can also be adjusted. However, such adjustments can only be made mechanically when the machine is not running, and there is no effective way to adjust the geometry of the wound package during operation. Such shortcomings are significant not only from a labor and production standpoint, but also from the viewpoint of the end use of the package.
For yarn dyeing, for example, a precision wound package is more likely to permit an easier flow of dye liquor from the interior of the core through the packaged yarn to the exterior of the yarn package than a random wound package of yarn. Unfortunately, even yarn packages which are precision wound using conventional techniques, such as by the Scharer winder, do not consistently produce a controllable density profile for the yarn package. In random winding, for example, the yarn is wound over the circumference of the support by tangential friction at an angle determined by the constant groove pattern in the drum. As the package diameter increases, the length of yarn delivered for a wrap also increases so that the distance along the support between the beginning and the end of a wrap must also increase to maintain the ratio contrast. Therefore, the number of wraps is highest next to the tube and this number gradually decreases as the diameter of the package increases. Since wrapping is produced through friction; therefore the larger the number of wraps will result in the larger amount of friction. And, since increased friction will result in increased density, it ensues that the density in a random wound package will be at its highest in the layers next to the tube and that density will gradually decrease as the diameter of the package increases. In addition, so-called "ribbons" are formed when successive layers of yarn accumulate on top of or adjacent one another. The yarn density of such ribbons is higher than that of the package, thus interfering with liquor flow through the yarn mass during dyeing. While mechanical expedients have been tried with some success, the density of the yarn package is not readily mechanically controllable during random winding. In contrast, during precision winding, package density is not regulated by friction. On the contrary, a slightly lower density of the yarn layers next to the tube results from a relatively slow speed during the first few seconds of a machine start. That density remains relatively constant throughout the package.
Thus, it is an overall objective of this invention to provide controlled electronic programmable winding for yarn packages. Such an invention would be useful to increase the productivity and the quality of yarn dyeing by controlling the density profile for the yarn package with favorable results. For example, a consequence of a low pressure drop across the yarn package during dyeing is that the yarn mass in the dyeing machine can be increased, thereby effectively increasing the yarn capacity and dyeing capacity of the dyeing machine. Moreover, the package geometry can be improvedly controlled according to the invention.
It is another general objective of this invention to provide a method for controlled electronically-programmed winding for packaging yarns.
It is still another objective of this invention to provide a method and apparatus for winding yarn according to a program implemented through an electronic apparatus to provide a predetermined density profile to the packaged yarn.
It is still another objective of this invention to provide a method and apparatus for controlling yarn package geometry by electrically controlling the tension on the yarn during winding according to a predetermined program to provide a particular geometry and density profile to the yarn package.
It is still another objective of this invention to provide a method and apparatus for controlling yarn package geometry and its density profile by electronically controlling, by a predetermined program, the tension on the yarn.
These and other objectives of this invention will become apparent from the detailed description of the invention which follows, taken in conjunction with the accompanying drawings.